The adhesion between fiber posts and root canal walls: comparison between microtensile and push‐out bond strength measurements

Abstract

Aim of the study was to compare the trimming and non-trimming variants of the microtensile technique with the 'micro' push-out test in the ability to measure accurately the bond strength of fiber posts luted inside root canals. In 15 endodontically treated teeth (Group A), fiber posts were cemented with Excite DSC in combination with Variolink II (Ivoclar-Vivadent). In 15 roots RelyX Unicem (3M-ESPE) was used for fiber post luting (Group B). Within each group, the bond strength of cemented fiber posts was assessed with the trimming and non-trimming microtensile technique, as well as with the push-out test. The great number of premature failures (16.9% in Group A, 27.5% in Group B) and the finding of high standard deviation values make questionable the reliability of the trimming microtensile technique. With the non-trimming microtensile technique, only five sticks were obtained from a total of six roots. The remaining specimens failed prematurely during the cutting phase. With the push-out test no premature failure occurred, the variability of the data distribution was acceptable, and regional differences in bond strength among root levels could be assessed. Relatively low values of bond strength were, in general, recorded for luted fiber posts. In conclusion, when measuring the bond strength of luted fiber posts, the push-out test appears to be more dependable than the microtensile technique.

Effect of endodontic chelating solutions on the bond strength of endodontic sealers

“…2,15 The push-out test is an efficient and reliable technique to assess bond strength of root canal filling materials to root dentin. 16 Results obtained within the experimental conditions of the present study indicate that iRoot SP yields higher dentin bond strength than AH Plus, regardless of the irrigation regimens employed. This finding may be explained in part by the calcium silicate composition of iRoot SP, which helps minimize shrinkage during the setting process.…”

Effect of calcium hydroxide intracanal dressing on the bond strength of a resin-based endodontic sealer

“…Different mechanical methods of evaluation have been proposed, such as shear bond strength (14,15), microtensile bond strength (7) and push-out tests (9,13,16), and different values of bond strength have been reported, even for the same material. The push-out test was used in this study for being easy to reproduce, to interpret and also for being able to realistically record, at even low levels, the bond strength to dentin (17,18). The hypothesis that push-out tests are operator-dependent (19) was not considered, since the bonding procedures were made by the same operator.…”

Avaliação dos ensaios de microtração, push-out e pull-out: resistência de união entre pino de fibra e dentina radicular, análise de elementos finitos e microscopia confocal

“…A utilização de pinos de fibra para a retenção de peças protéticas e restauração de dentes tratados endodonticamente já está largamente difundida (1)(2)(3) .…”

“…Porém, as características histológicas da dentina do conduto radicular (7) , a composição das substâncias irrigadoras utilizadas no processo de descontaminação do conduto radicular (8) , o tipo de material de obturação endodôntica (9) , a secagem dentinária após condicionamento ácido (10) , as propriedades mecânicas dos diferentes materiais utilizados na cimentação de pinos e a polimerização dos agentes cimentantes em uma configuração cavitária desfavorável (2) são algumas das variáveis que fazem da cimentação dos pinos de fibra um complexo procedimento adesivo (2) .…”

“…Ele ainda permite a obtenção de vários corpos-de-prova de um único dente. Porém, para os ensaios de microtração usando pinos de fibra tem-se uma técnica sensível e alto número de falhas prematuras (2) .…”